Dual hydraulically actuated oil well packer

ABSTRACT

A simplified and efficient dual string hydraulically actuated packer assembly is disclosed which utilizes unitary tubular anchor means, compressible packer elements, and springloaded, shearable, ratcheting packer lock means.

Jen e1 a1. e8. 3, 1974 DUAL HYDRAULICALLY ACTUATED OIL 3,224,508 12/1965Cochran 166/120 WELL PACKER 3,288,218 11/1966 Young 166/120 X 3,370,6512/1968 Brown 166/120 x n ors: Marion Barney Jet1,Seag 3,381,752 5/1968Elliston 166/120 Dennis Mitchel Spriggs, Dallas, both 3,414,058 12/1968De Rochemont.... 166 120 Of Tex. 3,714,984 2/1973 Read..... 166/206 x3,739,849 6/1973 Meripol 166/216 Asslgneei Dresser Industries, -5Dallas, 3,804,164 4 1974 E1115 166/120 [22] Filed: Nov. 2, 1973 21 App].No.2 412,386

Primary ExaminerDavid H. Brown Attorney, Agent, or Firm-Michael J.Caddell [5 7] ABSTRACT A simplified and efficient dual stringhydraulically actuated packer assembly is disclosed which utilizesunitary tubular anchor means, compressible packer elements, andspringloaded, shearable, ratcheting packer lock means.

[56] References Cited UNITED STATES PATENTS 19 Claims, 35 DrawingFigures2,159,640 5/1939 Strom 166/122 6 9 4 61 2 1 j m L l I I I J PATENTEL 5531 74 sum 01 or 13 PATENTEL, E59 3 saw 02 or 13 PATENTEUEEB 3W4 saw our13 PATENTEL 3,851,705

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' SHEU 11-0113 DUAL HYDRAULICALLY ACTUATED OIL WELL PACKER BACKGROUND OFTHE INVENTION Often during the producing life of an oil well it becomesdesirable or necessary to produce from two or more different undergroundformations penetrated by the wellbore. This is commonly achieved throughthe use of packer assemblies containing two or more strings of conduitpassing therethrough.

An example of such apparatus is shown in US. Pat. No. 2,965,173 in whicha packer apparatus having dual conduit strings passing side-by-sidetherethrough has located on its outer surface resilient sealing cupshaving outwardly flared ends which are moved into sealing engagement byfluid pressure differentials above and below the cups.

Other types of multi-string packers include the inflatable or bladdertype such as disclosed in US. Pat. No. 2,991,833 and the hydraulicallyactuated, compressible element, multi-string packer such as disclosed inU.S. Pat. No. 3,167,127. All known multi-string packers using mechanicalanchors to lock the assembly to the casing wall utilize the wedge-typeslip segments having teeth which are cammed or wedged into contact withthe casing wall by the action of a wedging mandrel being forced insidethe slip segments forcing them outwardly into contact with the casing.Other known types of slips include the hydraulic button type which arespring-retained radial pistons slidably located in the wall of thepacker body and actuated outwardly against the spring retainer byhydraulic force applied from inside the packer assembly. An example ofthe button type slips is shown in US. Pat. No. 3,31l,l69.

The dual-string or dual-conduit packers normally are used with astandard single string packer located on the tubing string below thedual-packer, which tubing string communicates with a lower formationbelow the standard packer and is connected to one conduit in the dualpacker and from there to a tubing string passing to the surface. Thesecond formation is normally located between the standard packer and thedual packer and can be produced through the second conduit pass-. ingthrough the dual packer and communicating with a second tubing stringextending to the surface.

The disadvantages of the prior art dual string packers are theircomplexity, extended length, and the tendency of the wedge-type slips tobecome disengaged by shifting or stretching of the tubing and/or casingduring the production life of the packer. 4

These and other disadvantages of prior devices are overcome by thepresent invention which comprises a dual string packer having simplifieddesign, shortened length, and highly efficient tubular unitary slipmeans.

BRIEF DESCRIPTION OF THE DRAWINGS I FIG. I is a top view of the dualpacker assembly;

FIG. 5, shows an axial cross-sectional view of the assembly taken atline 5-5 of FIG. 2;

FIG. 6 is across-section side view of the improved unitary tubular slip;

FIG. 7 is a top view of the improved unitary slip;

FIG. 7a is a side view of the improved unitary slip;

FIG. 8 illustrates a cross-sectional view of the apparatus in itsengaged position;

FIG. 9 illustrates the top view of an alternate embodiment of theapparatus;

FIGS. 10A through 10C comprise a cross-sectional view of the embodimentof FIG. 9 taken at line 10-10 in FIG. 8;

FIGS. 11a through He are cross-sectional views of the embodiment of FIG.9 taken at line 1l-l1;

FIG. 11d is a cross-sectional axial view of a key retaining sleeve;

FIG. ll la is a side cross-sectional view of a key retaining sleeve;

FIG. 11f is an axial end view of a retaining key;

FIGS. 12A through 12C comprise a cross-sectional view of the embodimentof FIG. 9 taken at line l212 of FIG. 9;

FIG. 13 is an isometric view of the shearable ratchet pins;

FIG. 14 is an isometric view of one of the setting cylinder releasingkeys in the piston assembly;

FIGS. 15a and 15b are schematic cross-sectional views of the grippingteeth on the anchor slip; I

FIGS. 16a and 16b show axial and radial crosssectional views of thewedge-cone heads disassembled from the apparatus;-

FIG. 17 illustrates a cross-sectional view of the slip of the secondembodiment;

FIG. 18 shows a side view of the slip of FIG. 17;

FIG. 19 is an axial cross-sectional view of a mandrel locking assembly;

FIG. 20 is a lateral cross-sectional side view of the mechanism of FIG.19 taken at line 20-20;

FIG. 21 is a lateral cross-sectional top view of the mechanism of FIG.19 taken at line 212l.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of theinvention is illustrated in FIGS. 1 through 5 in which a packer assembly1 is comprised of an upper mandrel assembly head 2,

' ing internal threaded sections 10a and 11a in which are threadedlyengaged the cylindrical tubular elongated mandrels 7 and 8. A receivercollar 12 is connected by bolts 13 to mandrel head 9 and has borepassages 10b and 11b coinciding and axially aligned with passages 10 and11 of head 9. Collar 12 has a concave cupped upper surface 12a arrangedto guide a tubing string connector 14 into bore 11b of the assembly.Mandrel head 9 further has a threaded internal section 10c adaptedtoreceive a section of conduit-or tubing in threaded engagement therein.

Tubular mandrels 7 and 8, fixedly attached by threaded connection tohead 9, extend in parallel relationship to the longitudinal axis of thepacker assembly 1 and generally parallel to the well-bore and havebottom threaded sections 7a and 80 extending downward out of the pistonassembly 6 whereby either or both may be threadedly engaged into a lowertubing string extending downward into the wellbore.

Slidably mounted on mandrels 7 and 8 are, in descending order, the upperunitary slip 4, upper packer head 31, one or more resilient packerelements 32, and lower packer head 33. Upper and lower packer heads 31and 33 are metal cylindrical plates having a cupped surface on one sideand having two axial bores therethrough for receiving mandrels 7 and 3.

' Resilient packer elements 32 are made of a resilient material such assynthetic rubber and are generally cylindrical, with dual bore passagespassing axially therethrough to snugly receive mandrels 7 and 8. Packerelements 32 are located in close fitting relationship with each otherand with the cupped surfaces of plates 31 and 33. A flanged retainerring 341 abutting an external shoulder 16 on mandrel 8 limits downwardmovement of the resilient packer assembly 3 on the mandrels by alsoabutting the lower surface of lower head 33.

Lower unitary slip is located on the mandrels in encircling relationshipabout the mandrels and slidably mounted thereon; slip 5 is similar toslip 4 but is mounted on the mandrels in an inverted orientation to slip4.

Piston assembly 6 is mounted on mandrels 7 and 8 in encirclingrelationship and consists of cylindrical setting piston 61 andcylindrical setting cylinder 62. Setting piston 61 is a substantiallysolid cylindrical piece having dual axial bore passages therethrough toreceive mandrels 7 and 8 and an upper annular space 63 around mandrel 8.Referring to FIG. 5, setting piston 61, as shown in cross-section, has aplurality of transverse lateral cylindrical bore passages 64intersecting the longitudinal axis of bore passage 11 and havinginternal helical threads. Shearable cylindrical ratchet pins 65 areslidably located in passages 64 and are urged into engagement withmandrel 8 by the expansive forces of leaf, helical, or bellevillesprings 66 which are held in compression against pins 65 by abuttingengagement with threaded plugs 67 which are snugly secured into threadedpassages 64.

Pins 65 have a reduced section 65a designed to shear at a predeterminedload and a toothed ratchet head 65b having a curved face adapted tomatch the curvature of mandrel 8, with a plurality of cammed teeth 65cthereon designed to match and engage external annular teeth 8b formed onmandrel 8. FIG. 13 illustrates a second view of the shearable ratchetpins showing the relationship of the teeth 650 on ratchet head 65b. Theteeth 8b and those on head 65!) are arranged to allow upward movement ofthe pins on mandrel 8 but prevent downward movement of the pins and thusprevent downward movement of piston 61. The cammed faces of teeth 8b and650 allow the piston 61 to move upward by camming the pins back againstthe springs 66, compressing them and allowing the ratchet teeth to slideover one another. Upon attempted downward movement of piston 61 onmandrel 8 the perpendicular faces of teeth 65c abut the perpendicularfaces of teeth 8b and prevent the backward motion. Further operation andfunction of the ratcheting arrangement will be described in connectionwith operation of the entire packer assembly.

Setting cylinder 62 is a cylindrical element having a substantiallysolid'lower section 62a and an upwardly extending outer collar 62bpassing exteriorly around piston 61. Lower section 62a is solid exceptfor two longitudinal bore passages therethrough which receive in snugslidable relationship the mandrels 7 and 8. Cylinder 62 is temporarilyattached to piston 61 by means of a plurality of shear pins 68 passingthrough upper collar 62b in threaded engagement therewith and seating inexterior channel 61a passing circumferentially around piston 61.

Setting cylinder 62 is temporarily attached to mandrel 8 by means of aplurality of curved locking keys 69 having inwardly projecting shoulder69a thereon for engaging a matching exterior channel in mandrel 8. Keys69 are held inward by overlapping abutment of annular shoulder 61b onthe lower end of piston 61. The keys, by abutment with the groovedchannel in mandrel 8, the lower end of piston 61, and the upper end ofsolid end 62a of cylinder 62 temporarily prevent any sliding motion ofthe piston assembly 6 with respect to mandrels 7 and 8. One or moreports are located through the wall of mandrel 8 to communicate with thearea between piston 61 and cylinder end 62a from bore 11 to release keys69 in a manner which will be more fully described in relation to theoperation of this tool.

At the lower end of mandrel 8 on external threaded end 8a is a standardthreaded collar 19 attached thereto containing a valve seat 21 forreceiving a fluid valve member such as a ball or plug, arranged toselectively close passage 11 to fluid flow through mandrel 8 and allowfluidic pressure to be applied through ports 80.

Referring specifically to FIGS. 2 and 4, the tubing string connector 14is more particularly described as a cylindrical tubular upper sleeve 14chaving internal threads 14a for engaging a standard conduit section andan annular external depression 14b for receiving a seal carrier ring 15.A lower spring collet sleeve 16 is threadedly attached at 16a to theupper sleeve 14c and has collar 16b thereon for abutting and retainingcarrier ring 15 which has a plurality of circular seals 17 thereon forsealing engagement between connector 14 and head 9.

Collet sleeve 16 is temporarily restrained in head 9 by the abutment ofannular exterior shoulder 16c with interior annular projection 9a inhead 9. Removal of shoulder 16c upward past projection 9a can beaccomplished by application of a predetermined lifting force whichcauses inward deflection of the shoulder 16c and allows it to moveupward past projection 9a. Deflection inward of shoulder is madepossible by the forming of several longitudinal slots 16d in colletsleeve 16 thereby lending flexibility to the metal remaining in theareas between the slots. The amount of lifting force required to movecollet sleeve 16 out of head 9 can be adjusted as desired by the numberand/or width of slots 16d and/or the angle of engagement between 160 and9a.

Referring now to FIGS. 6, 7, 7a, 15a, and 15b, a more detaileddescription of the improved unitary slip members can be given. Each slip4 and 5 comprises a generally cylindrical gripping unit having on theextended outer reaches of opposing sides a plurality of teeth 41 curvedabout the slip body with an axis of curvature at an angle to the centrallongitudinal axis of the slip member. The teeth are also arranged sothat the intersection of a plane passing through theslip longitudinalaxis with the teeth extreme outer tips would circumscribe a curve asshown in FIGS. a and 15b. This is to allow the use of this apparatus incasings having varying inner diameters and obviates the need for aseparate set of unitary slips for each weight rating of easing. Insmaller ID casings, as shown in FIG. 15a, i.e., those of heavier weight,the two sets of teeth near the center of the slip, having the shortestdistance between them will contact the casing wall with greatest areacontact; while in larger ID, lighter weight casing as shown in FIG. 15b,the teeth at the two outer ends of the slip will contact the casing dueto the greater distance between the upper outer teeth and the lowerouter teeth.

The curved boundary tooth profile as shown in FIGS. 15a and 15b allowsthis versatility of use by providing greater tooth-casing wall contactarea regardless of which teeth are called upon to anchor the packerassembly.

Looking at FIGS. 6, 7 and 7a, it is clear that each unitary slip has adual-axis bore passage for each mandrel to pass therethrough. One axisof each bore passage generally parallels the central longitudinal axisof the slip and the other axis is located at an angle thereto in thesame plane.

In FIG. 6, the intersecting bore passages are illustrated more clearlyand their longitudinal axes are designated as XX and Y--Y. This view istaken from the side with the two mandrels lying in line with one anotherso that only one can be seen in cross section. The axis X-X defines borepassages 43 which are shown by 1 the dashed lines in the figure. Whenthe slip is oriented so that the mandrels occupy these bore passages,the gripping teeth are at their innermost orientation, out of contactwith the casing wall.

When the slip has been rotated to bring the passages 44 into fittingrelationship with the mandrels, then the gripping teeth are at theiroutermost extension from the mandrels and can engage the casing wall.Bore passages 44 are shown by the solid lines in the figure.

The angle between axes XX and Y-Y can be from 5 up to about 35 butpreferably is around 18 to 20?.

Referring specifically to FIG. 6, a significant improvement in theunitary anchor slip 5 is illustrated-in the cross-sectional view whichshows the abutment surface 51. This surface is at the opposite end ofthe slip from abutment edge 52 and provides a dual purpose surface onthe slip.

Rotation of the slip into casing engagement is achieved'by moving anabutment means such as piston 61 against compound surface 51 which movesthe slip along the mandrel until abutment edge 52 encounters an opposingabutment surface. The resultant effect is a rotational momentestablished in the slip from the reactant force on edge 52. This isaided by abutment forces introduced into the slip from surface 51.

Surface 51 has been termed a dual or compound surface. This is becauseof the flat portion 51a and the tangentially curved section 51b joiningthe flat surface. The curve of surface 51b is preferably on a radius Rsubstantially equivalent to rL where L is the axial length of the slipalong axis XX. The curved surface is tangential to flat surface 51a atthe point where axis -X-X intersects the end of the slip at surface 51.

The slip is arranged to pivot about a point C located at theintersection of axes X-X and Y-Y at a distance of approximately ra ofthe slip length L from surface 51.

A phantom line P is drawn on the slip at the edge containing surface 51bto indicate the construction of the prior art slip means. Such a slip isdisclosed in US. Pat. No. 3,739,849 to Robert B. Meripol. While the slipof that disclosure is a significant improvement over the art, theexistence of the extended shoulder P requires significant additionalapparatus in the packer on which it is used.

Primarily a significant clearance must be maintained with the prior artslip between the slip in its unset position and the lower abutment meansto allow pivoting of the slip into casing engagement position. This isbecause the radius Rp is considerably greater than the distance VzL andtherefore a minimum clearance equivalent to Rp R must be maintainedbelow the flat surface of the prior art slip to allow it to rotate intothe set position.

To maintain the clearance and also to support the slip in a rotatableposition and allow a moment force to be applied to abutment surface 52without driving the slip downward on the abutment surface, the prior artslip was necessarily supported by pivot pins at C which passed throughthe slip and were engaged in an inner support sleeve. The downward forceat 52 was countered by the oppositely reacting upward force of the pinson the slip which set up the desired rotational moment. The inner sleeveand the pins also served to hold the slip up off of the lower abutmentmeans so that it could be pivoted. The inner sleeve and pivot supportpins are illustrated in FIG. 1 of the aforementioned Meripol patent anddesignated therein as 20 and 34 respectively. The clearance under theslip is not illustrated in that figure since the slip has been rotatedto the engaging position.

The improved slip of this invention eliminates the need for thesupporting sleeve, the pivot pins, and the pivot clearance necessary tothe prior art device.

Since the radius of the curvature of surface 51b about the pivot centerC is equivalent to the distance of surface 51a from C, it is obviousthat the slip 5 can be pivoted about C in the same space as thatoccupied by the slip in the unset position. This eliminates the need forthe support sleeve, the pins, and the clearance below surface 51.Furthermore surface 51 may remain in constant abutment with adjacentabutment means to provide the necessary rotational moment from forces onsurface 52 which further obviates the need for support pins at C.

Another advantage of the improved slip is in the guaranteed setting ofthe slip. In the aforementioned patented slip, should the clearancebelow the slip ever be decreased due to stretching of the parts,accumulated debris in the clearance area, failure of one or more of theparts, or incorrect assembly of the tool during manufacture, to-thepoint where the clearance is substantially less than the amount Rp L, itis clear that edge P will abut the lower surface or the debris inopposition to the setting forces at edge 52 and the desired rotationalmoment about C will be cancelled.

This situation is non-existent since the slip can rotate without theneeded clearance and due to the simplicity of having no pins, norsleeves; and incorrect assembly and part failure are almost absolutelyeliminated.

One further advantage of the improved slip is that, when used as thelower slip, should it become lodged in the casing to the point that thereleasing spring 4% hereinafter described is insufficient to rotate itout of engagement, dislodgement can be accomplished by merely bumpingupward on the slip with the lower abutment means. Since some point onthe curved surface 5lb will be located directly below C and will receivethe upward abutment it is clear that no rotational moment will beintroduced into the slip, and the simple upward driving force, inaddition to the disengaging force of the releasing spring 49b willdislodge the slip from the casing. The upper surface 52 will of coursebe free from abutment during this releasing step.

Although the slip 5 has been described above, it is emphasized that slip4 is identical to slip 5 and operates in the same manner, and the abovedescription appertains thereto as well. Thus it can be seen that thesetwo side-by-side ,dual bore passages and the compound curved-flatabutment surface 51 allow the unitary slip to pivot about the twoparallel mandrels 7 and 8 from a non-engaging position to a casingcontact position without any interference between the slips and themandrels.

Each slip also has a releasing slot 46 as shown in FIG. 3 which runspartially the length of the slip and passes through the wall thereof ina plane perpendicular to the plane of the two dual-axis bore passagesand the central slip axis. A third bore passage 47 passes from the innerterminal wall 460 of the slot 46 through the slip to the opposite end.The cross-sectional view of FIG. 3 reveals the purpose of slot 46 andpassage 47 to be for the location of the threaded L-shaped releasing lug48 and release spring 48a in the upper slip 4; and in the lower slip 5,retaining bolt 49, flanged bolt collar 49a, and

coil spring 49b. A spring cavity 490 is formed in each slip and a springcavity 48b is formed in the L-shaped bolt to receive coil spring 48a.Lug 48 passes through passage 67 and is threadedly secured into thelower end of head 9. Likewise, bolt 49 passes through passage 47 of thelower slip 5 and is threadedly secured to the upper end of settingposition 61.

In FIGS. 2 through 5 the packer assembly is illus- I trated in its unsetorientation with the mandrels 7 and 8 lying in bore passages 43 parallelto the central longitudinalaxis. In FIG. 8 the packer apparatus has beenactivated and expanded into sealing and anchoring engagement with thecasing wall. In this position, the slips have been rotated to bring themandrels into the second bore passages 44 at the angle to thelongitudinal bore passages 43 mentioned above.

OPERATION OF THE PREFERRED EMBODIMENT I packer apparatus 1 is loweredinto the well until the lower packer passes the upper producingformation and is situated between the two subject formations. The packerapparatus 1 will be located above the upper producing formation.

By appropriate means, such as manipulation of the tubing or hydraulicpressure applications, the lower packer is set in the casing.Altemately, the lower packer may be set by wireline or other meansbefore the primary and secondary tubing strings are lowered into thehole and then the primary string can be stung into the lower packer. Thesecond production string may then be lowered down the well with theconnector sleeve 14 threadedly attached at the lower end. When thestring has been lowered sufficiently, the sleeve 14 will engage head 9and snap into place. The second string will then be sealinglycommunicating with mandrel 8 via bore 11 of head 9.-

A sealing ball or plug 20 is dropped run in on a wireline, or pumpedinto the secondary tubing string to seal on seat 21 and allow fluidpressure to be applied to the fluid in the secondary string and actthrough bore 11 and ports 80 against the lower end of the setting piston61. When sufficient pressure has been reached in bore 11, piston 61 willshear pins 68 and move upward against the lower edge 51 of lower slip 5sliding the slip upward until upper abutment edge 52 of the slipcontacts the lower edge of lower head 33. Movement upward of piston 61on mandrel 8 is allowed by the ratcheting action of ratchet pins 65 overmandrel teeth 8b which ratchet mechanism simultaneously preventsdownward movement of piston 61 on mandrel 8 under normal operatingconditions.

As piston 61 moves upward in response to hydraulic pressure actingupward, the upward force is transferred to lower slip 5, and from slip 5to packer elements 3 and into the upper slip 4. This abutment of theslips I with the packer assembly serves to rotate the slips into contactwith the casing simultaneously with compression of the packer elements32. Thus, continued application of hydraulic pressure of sufficientmagnitude for a short period of time will set the two unitary slips intothe casing and will expand the resilient packer elements outward intosealing engagement with the casing as shown in FIG. 8.

Upon release of hydraulic pressure in bore 1 1, the re silient packerelements will attempt to expand longitudinally and contract radially.This will provide a constant upward force on slip 4 and a constantdownward force on slip 5 maintaining them engaged in the casing.

Y Also, ratchet pins 65 will maintain mandrel 8 telescoped within piston61 thereby preventing the packer from unsetting should mandrel 8 try tomove upward in the wellbore for any reason.

Should it become desirable to unseat the packer apparatus 1, this can bedone selectively by applying an upward force on mandrel 7 and thus onmandrel 8 sufficient to shear pins 65 through their reduced area 65a. Inorder to prevent a bending or collapsing of shear head 65b along the gapat 65a, a relatively soft filler material such as lead or plastic can befilled in the gap at 65a to absorb the bending moment and insure propershearing of the pins.

Upon shearing pins 65 mandrels 7 and 8 move upward with respect to theslips 4 and 5 and packer assembly 3. Releasing lug 48 will move upwardand work through spring 480 to pivot upper slip 4 back to itsnonengaging position, also pulling it upward off of the packer assembly3, allowing the resilient packer elements to contract to their normalunseated orientation.

Continued upward movement of the mandrels 7 and 8 will disengage thelower head 33 from abutment shoulder 52 of slip allowing disengagementof the lower slip from the casing. Coil spring 49b will then expandagainst slip 5, thereby pivoting slip 5 into its retracted position. Thepacker assembly 1 is now completely unset and may be removed from thehole. The secondary tubing string may be removed from passage 11 beforeor after unsetting the packer assembly 1, or may be removed from thehole with the primary string if desirable.

MANDREL LOCKING MEANS FOR HIGH WELL PRESSURES Occasionally the apparatusof this invention must be used in a well having extremely high formationpressures or used in treatments of wells whereby fluids under highpressure must be pumped into the well formations through this apparatus.

For instance, pressures below the above described packer assembly mayreach the range of 5000 PSI or higher, and in this range a considerableupward force is exerted by the fluid upon the conduit strings in thewellbore, creating a buoyancy effect on the packer mandrels tending todrive them upward through the packer assembly resulting in unsetting ofthe slips and consequently the packer elements. This buoyancy effect istermed the piston" or end area effect.

To avoid this tendency towards disengagement of the slips caused by thepipe bouyancy, a special locking mechanism is provided which is actuatedby pressure below the packer elements and serves to lock the mandrels inthe packer assembly.

Referring to FIGS. 19, 20, and 21 the locking mechanism is illustrated.FIG. 19 is an axial view in crosssection taken at line 19-19 of FIG. 20.In the modified embodiment, the packer assembly 3 of FIGS. 1-4 isreplaced by the modified locking packer assembly 203. Packer assembly203 consists essentially of an upper head 231, resilient packer elements232 and lower head 233, all encircling mandrel 7 and modified mandrel208.

Modified mandrel 208 is substantially similar to mandrel 8 except fortheexistence of a plurality of tooth ridges 210 formed in the outersurface of the mandrel. Each ridge 210 has an abrupt upper face 210a anda sloping lower face 210b. The angle that face 210a makes with a planenormal to the tubular axis of mandrel 208 is preferably about tendegrees butmay vary from one to forty degrees depending upon the amountof restraining force desired. The angle of face 210!) with face 210a maybe from l30 to about 50 with a preferable angle of around 90. Ridges 210preferably circle mandrel 208 entirely but this is not absolutelyessential.

The packer assembly 203 contains two fluid bore passages 204 and 205passing through lower head 233, resilient packer elements 232, and partof the way into upper head 231. The bore passages generally run parallelto the mandrels 7 and 208 and communicate with the formation annulararea below the packer assembly 203.

Rigid tubes 206 and 207 line the bores through the resilient elements232 to prevent collapse and closure of the passages upon compression anddeformation of the resilient packer elements.

The bore passages 204 and 205 intersect pin channels 211 and 212 passingfrom the-longitudinal bore passage 209 in head 231 containing mandrel208, going radially outward from mandrel 208 through head 231 andthrough the outer surface of the head.

The radial passages 211 and 212 contain outer threaded portions 211a and212a and smooth piston sections 2l1b and 212b. The radial passagespreferably are of a cylindrical configuration for ease and convenienceof manufacture but may be of any reasonable configuration.

Located slidably in piston sections 211b and 212b of the radial passagesare locking pistons 213 and 214 having curved toothed faces 213a and2140. The teeth on these faces match and complement the teeth of mandrel208 so that full surface contact between the two sets of teeth willoccur. The radius of curvature of faces 213a and 214a is substantiallyequal to that of the outer surface of mandrel 208.

Threaded sections 211a and 212a contain threaded plugs 215 and 216snugly engaged therein in sealing contact, which plugs, in conjunctionwith pistons 213 and 214, serve to form hydraulic expansion chambers 217and 218 in each radial passage. Circular seals 219 and 220 in the outerwall of pistons 213 and 214 serve to prevent leakage of fluid from theexpansion chambers into the mandrel bore passage 209.

Operation of the locking mechanism is automatic when this modifiedembodiment of packer mechanism 203 is installed in the previouslydescribed packer apparatus 1, and consists of hydraulic pressure fromthe annular area below the packer mechanism 203 communicating throughbores 204 and 205 and into pressure actuation chambers 217 and 218. Thepressure is prevented from moving radially outward by plugs 215 and 216and therefore it acts inwardly against the pistons 213 and 214 drivingthem against the mandrel teeth 210 thereby gripping the mandrel 208 andholding it in the packer assembly 203.

Since the packer anchors 4 and 5 are normally released by pulling upwardon the tubing strings and thus on the mandrels, the angle of faces 210aon the mandrel teeth should be around five to fifteen degrees to allowupward movement of the mandrels upon application of external liftingforce on the mandrels. Also, the pressure area of piston faces 213 and214 may be designed so that the gripping force of the piston teeth onthe mandrel teeth is just equalto or slightly greater than the buoyantupward force on the mandrels so that little additional upward lifting ofthe mandrels is required to wedge the piston teeth out of engagementwith the mandrel teeth when unsetting the packer to remove it from thewellbore.

It should be noted that the back or lower edges 2101) of the mandrelteeth are at a relatively flat angle compared to the upper faces 210a sothat movement of the upper head upward on the mandrels is hardlyimpeded.

In addition to the hydraulic force on pistons 213 and 214 it is clearthat any known spring means such as coil springs could be compressed andplaced in chambers 217 and 218 to supplement the actuating pressure.

ALTERNATE EMBODIMENTS Referring now to FIGS. 9 through 12 and 16 through18, an alternate embodiment of the invention is disclosed which utilizesa single unitary slip or anchor capable of anchoring the assembly in thecasing against upward and downward forces and pressures.

The packer apparatus 101 essentially comprises upper connector assembly102, upper head assembly 103, packer assembly 104, unitary slip 105, andpiston assembly 106. I

The upper connector assembly 102 features a primary tubing receiver 110which is an elongated tubular member having external threads 1100 and110b at its upper and lower ends and containing a connector collar 111threadedly attached to threads 110a and arranged to be interconnectedinto a standard tubing string. Tubing receiver 110 is threaded intoupper head 112 which also receives in threaded engagement a tubularelongated secondary tubing string receiver 113. Head 112 is primarily acylindrical member having dual bore passages passing therethroughoriented substantially parallel with the central longitudinal axis ofthe cylindrical member. The upper portions of the dual bore passageshave internal threads 112a for receiving tubular sections 110 and 113.

Tubular receiving member 113 has an enlarged chamber area 114 attachedto a standard tubular section or neck 115 and containing an annularinwardly projecting shoulder 116. Threadedly attached to the upper endof member 113 at threads 113a and slidably encircling member 110 isupper receiver dish 117 which is a generally cylindrical section havinga concave upper face 121 and dual bore passages 119 and 120 to receivemember 110 and the secondary tubing string collet sleeve 118. Colletsleeve 118 is a tubular member having an annular shoulder 123 sized toabut shoulder 116 and be retained thereby. Longitudinal slots 122 areformed through the wall to give the remainder of the sleeve flexibilityand allow shoulder 123 to flex inward and traverse shoulder 116. Acylindrical, tubular seal carrier collar 124 is threadedly attached tosleeve 118 and contains seal elements 125 encircled thereon to sealagainst bore 114 of receiver 113. A standard length of tubing 126 can bethreadedly attached into collar 124.

Upper head 112 contains inner annular abutment ridges 112b in borepassages 130 and 131 to receive in snug fitting relationship the primaryand secondary mandrels 107 and 108 which mandrels are elongatedcylindrical tubular members extending substantially through the entiretool.

Each mandrel 107 and 108 has an annular exterior shear shoulder 107a and108a for abutment with and selective shear means for shear screws 127which project through the wall of head 112 and into the shear chamber128 formed between head 112, shoulders 107a and 108a and mandrels 107and 108. v

A cylindrical abutment shell 129 is secured to head 112 by threadedbolts 132 passing through the head and threadedly engaging shell 129 asshown in the discontinuous cross-sectional view of FIG. 9. This crosssection must be shown in broken or discontinuous sec-1 tion in order toshow the bolts since a normal cross section at line -10 of FIG. 9 wouldnot clearly show them.

Located axially within shell 129 are two parallel locking-key retainersleeves 133 and 134 which are relatively thin cylindrical sleeves havingflats milled along diametrically opposing sides and placed side by sideslidably telescoped over mandrels 107 and 108. The milled sides areshown in cross section in FIG. 12 and the normal sides are shown in FIG.10. FIG. 11d shows a cross-sectional axial view of one of thekey-retaining sleeves 133 and 134, and FIG. 11c shows a crosssectionalaxial view of a sleeve.

Shell 129 also consists of a thick wall area and a thin wall area asshown in FIGS. 11 and 12. The narrowed walls of shell 129 and of sleeves133 and 134 are to allow side by side placement of the two mandrels 107and 108 within the dimensions of the sleeves and the shell. Shell 129has at its lower end an inwardly projecting flange 129a through whichpass locking collet sleeves 135 and packer assembly bolts 136concentrically located within sleeves 135.

Sleeves 135 each have a small spring lip 1350 on the outer edge of theupper end for engaging flange 129a and an outer abutment flange 135b atthe lower end for abutment and retention of upper packer plate 137 tohead 112. This prevents head 112 from floating upward on bolts 136 awayfrom plate 137 and prematurely shearing of screws 127 while going in thehole with the tool.

Key-retaining sleeves 133 and 134 are arranged so that slots in thesleeves are located directly over parallel, exterior circumferentialridges 138 and 139 on mandrels 107 and 108. Retaining keys 140 aresnugly fitted within the slots and abut the mandrels between the ridgesas shown in FIG. 9. This arrangement temporarily locks the mandrels tothe upper head assembly 103 by means of keys 140, ridges 138 and 139 andsleeves 133 and 134 and allows the operator to pick up on the string andreciprocate it to dislodge sediment or other material which may bebinding between the tool string and the casing while going in the hole.This protects shear pins 127 from premature shearing. Keys 140 are heldwithin the slots in sleeves 133 and 134 by abutment with the inner wallof the lower extending portion of head 112. FIGS. 11a 11c give views ofthe sleeves and keys disassembled from the apparatus for a'betterunderstanding of their structure.

The resilient packer assembly is located slidably about the mandrels 107and 108 below upper packer plate 137 and consists of resilient packerelements 141, rigid spacer plates 142 and lower packer plate 143..

A dual wedge-cone head 144 is abutted against lower plate 143 inencircling relationship about mandrels 107 and 108 and wedge anchors145. Anchors are wedge shaped inserts having a plurality of angledgripping teeth on their inner surface contacting the outer wall of themandrels.

Movement upward of the anchor inserts 145 on the mandrels is possiblebecause of the angle of the upper faces of the wedge teeth but movementdownward on the mandrels is prevented by the perpendicular teeth faceprojecting into the mandrel surface and also because of the wedgingforce inward imposed by the action of the wedge-cone head 144. It isclear that the angled inner surface 144a of head 144, acting on theangled outer surface 145a of the anchor 145 as the anchor moves upward,will result in a pressing inward of the anchor insert upon the mandrelit contacts thereby preventing downward movement of the mandrel. A

more detailed view of the dual wedge-cone head 144 is shown in FIGS. 16aand 16b.

Guide pins 146 project through head 144 and into slots 145b formed inthe outer portion of wedge inserts 145 to prevent the anchors fromrotating around on the mandrel and getting out of optimum grippingposition which is with each anchor diametrically opposed to anotheranchor about the mandrel.

1. A dual string oil well packer comprising: dual elongated tubularmandrels arranged in substantially parallel orientation, each having anintegral independent bore passage extending therethrough; upper bodymeans attached to and encircling said mandrels; unitary, tubular,pivotable anchor means located about said dual mandrels in encirclingrelationship and having a plurality of grooved teeth at opposing sidesof said anchor means; said anchor means arranged on said mandrels inlimited slidable and pivotable relationship whereby said anchor meanscan be rotated from casing engaging position to non-engaging position onsaid mandrels; packer means comprising a plurality of resilient annularpacker elements and rigid containing means adjacent said resilientelements, said packer means encircling said mandrels in a partiallyslidable relationship thereon and arranged to abut said anchor means;hydraulic actuation means located on said mandrels and comprising pistonmeans and cylinder means, said piston means slidably engaging saidcylinder means, and said piston means and said cylinder means eachcontaining inner annular differential pressure area surfaces arranged tocommunicate with port means through the wall of one of said mandrels;said differential pressure surfaces adapted to receive fluid pressurethrough said port means and force said piston means out of said cylindermeans into abutment with said anchor means thereby rotating said anchormeans and compressing said resilient packer elements into engagementwith the well casing; locking means on said mandrels for engaging saidmandrel and maintaining said anchor means in said rotated position andsaid packer means in said compressed position; shear meanspreselectively shearable to allow said anchor means and said packermeans to be released from said locking piston at a predetermined desiredtime; and, releasing means in said packer arranged to abut said rotatedengaged anchor means and selectively rotate said anchor means out ofengagement with said well casing.
 2. The well packer of claim 1 whereinsaid anchor means further comprises two unitary anchor slips each havinga generally cylindrical external configuration, with the first of saidslips arranged to grip the well casing in opposition to downward forceson said well packer and said second slip arranged to grip the wellcasing in opposition to upward forces on said well packer.
 3. The wellpacker of claim 2 wherein said unitary slips are located one above andone below said packer means with said upper slip arranged to opposeupward forces on said well packer when engaged, and said lower sliparranged to oppose downward movement of said well packer when engaged ina well casing, said well packer arranged to be set and sealed in a wellcasing by upward movement of said lower slip against said packer meansand downward movement of said upper slip against said packer meansthereby compressing said packer means into radial expansion against thewell casing and rotating said slips into anchoring engagement with thecasing.
 4. The well packer of claim 2 wherein each said anchor slip hasa plurality of gripping teeth located at diametrically opposed sides onopposite ends thereon and each anchor slip has two sets of dual parallelbore passages passing therethrough, with the first said set of passagesintersecting said second set at a predeterMined angle of about 5* to35*.
 5. The well packer of claim 4 wherein said locking means and saidshear means comprise one or more shearable ratcheting pins having cammedteeth formed at one end thereon and having a shearable cross-section atone point along the longitudinal axis thereof, said pins being springbiased against one of said mandrels, said mandrel abutting said pinsalso having cammed teeth thereon complementary to said cammed teeth onsaid pins; said pin teeth and said mandrel teeth arranged to allowratcheting longitudinal movement of said pins on said mandrels in onedirection while shearably preventing relative movement between them inthe opposite direction.
 6. The well packer of claim 5 wherein saidpiston means is initially attached to said cylinder means by shearablemeans, and said anchor slips are yieldably urged into a non-engagingposition in said casing by the interaction of coil spring means betweensaid slips and said releasing means.
 7. The well packer of claim 6wherein said releasing means comprises upper releasing means and lowerreleasing means; said upper releasing means further comprising firstbolt means attached to said upper body means and extending partiallythrough one of said anchor slips, said first bolt means having anabutment shoulder thereon for abutment with one of said anchor slips andarranged to rotate said anchor slip out of engagement with the casingupon abutment with said slip; and, said lower releasing means comprisingsecond bolt means passing through the other of said anchor slips andattached to said piston means, and abutment means on said second boltmeans arranged to abut said other slip and rotate it out of contact withthe casing wall.
 8. A multistring well packer assembly for sealing offmultiple sections of annular area in an oil well and communicatingconduit strings with each area; said well packer assembly comprising: aplurality of tubular elongated mandrels arranged generally in parallelrelationship and adapted to be placed longitudinally in a well bore; anupper head assembly fixedly attached to the upper ends of said tubularmandrels and containing bore passages therethrough communicating withsaid mandrels; said assembly adapted to be interconnected into aplurality of conduit strings in said well; an upper unitary anchor sliprotatably and slidably mounted on said mandrels below said upper headassembly, arranged to abut said upper head assembly, and having grippingteeth ridges formed on opposite sides at opposite ends arranged to bepivoted into gripping engagement with the well casing; expandible packermeans located in slidable encircling relationship about said mandrelsand containing resilient packer elements therein, said packer meansarranged to abut the lower end of said upper anchor slip and applyrotative force thereto; a lower unitary anchor slip slidably androtatably mounted on said mandrels below said packer means and arrangedto abut said packer means and rotate into gripping contact with the wellcasing; and a piston and cylinder assembly attached to said mandrelsbelow said lower anchor slip and adapted to receive hydraulic pressurefrom within one or more of said mandrels and apply upward abutment forceto said lower anchor slip and downward force to said mandrels.
 9. Thewell packer assembly of claim 8 further comprising upper slip anchorreleasing means in said upper anchor and lower slip anchor retractingmeans in said lower anchor; said upper releasing means and lowerretracting means comprising bolt means passing through each of saidanchors and having abutment means thereon, and spring means on said boltmeans arranged in cooperation with said abutment means to urge saidanchors into non-engaging position.
 10. The well packer assembly ofclaim 8 further comprising shearable ratcheting lock means in saidcylinder and on at least one of said mandrels, said lock meanscomprising a plurality of toothed shearable pins slidably located inradial bore passages in said cylinder and urged inward toward saidmandrel by spring means abutting said pins; and a plurality ofcircumferential cammed teeth on at least one of said mandrels arrangedto abut said teeth on said pins; said mandrel teeth and said pin teetheach having a perpendicular face and a cam face arranged to allowratcheting movement of said cylinder upward on said mandrel whileshearably limiting downward movement thereon.
 11. The well packerassembly of claim 8 wherein said piston and cylinder assembly comprisesan elongated tubular cylinder temporarily securedly attached to saidmandrels, and a slidable cylindrical piston encircling said mandrels andshearably attached to said cylinder and partially telescopically locatedtherein; said piston and said cylinder having opposing differentialpressure areas therein; and one or more of said mandrels having portsthrough the wall communicating with said opposing differential pressureareas, said differential pressure areas arranged to respond to hydraulicpressure through said ports and move said piston upward into abutmentwith said lower anchor slip and move said cylinder downward.
 12. Thewell packer assembly of claim 11 wherein said piston and cylinderassembly further comprises locking key means between said piston andcylinder assembly and one of said mandrels, said locking key meansarranged to simultaneously abut said mandrel, said cylinder, and saidpiston and thereby prevent sliding movement of said piston and cylinderassembly on said mandrel; said locking key means further arranged to bewedged out of abutment with said mandrel upon movement of said pistonout of said cylinder.
 13. The well packer assembly of claim 8 furthercomprising hydraulic locking means in said expandable packer meansadapted to receive hydraulic pressure from below said expandable packermeans and applying restraining forces to said mandrels, whereby upwardbuoyant movement of said mandrels resulting from high pressurestherebelow are restrained by said hydraulic locking means.
 14. The wellpacker assembly of claim 13 wherein said hydraulic locking means furthercomprise: flow passage means passing upward from the lower end of saidexpandable packer means; radial bore means in said packer meanscommunicating said flow passage means with at least one of saidmandrels; and piston means in said radial bore means responsive tohydraulic pressure from said flow passage means and arranged to abutsaid at least one mandrel in restraining engagement.
 15. The well packerassembly of claim 14 wherein said piston means further comprises one ormore elongated pistons having seal means thereon sealingly engaging saidradial bore means, said pistons slidably located in said bore means andhaving a plurality of mandrel engaging teeth on the inward surfacethereof adapted to abut said at least one mandrel upon application offluid pressure to the outer ends of said pistons, said mandrel havingcomplementary teeth means thereon adapted to engage said teeth on saidpistons.
 16. In a well packer of the type having mandrel means, withpivotable anchor means and expandable resilient casing sealing meanslocated on said mandrel means, the improvement comprising hydrauliclocking means in said expandable sealing means arranged to receivepressure from below said sealing means and apply a gripping force tosaid mandrel means.
 17. The well packer of claim 16 wherein saidhydraulic locking means comprises piston means slidably located in saidexpandable sealing means and arranged to receive hydraulic pressure on aradially outward end of said piston means and, in response to saidpressure, abut said mandrel means.
 18. The well packer of claim 17wherein said piston means comprises a plurality of elongated cylindricalpiston members mounted in bore passages extending radially outward fromsaid mandrels; said piston members sealingly mounted in said radial borepassages and having gripping means on the inner surfaces thereofarranged to abut said mandrels.
 19. The well packer of claim 18 whereinsaid gripping means comprises a plurality of teeth each having an abruptlower face and slanted upper face with the lower face making an angle offrom 60* to 90* with said mandrel means central longitudinal axis; andsaid mandrel means having external peripheral ridges thereon with anglescomplementary to said teeth and being arranged to engage said teeth uponabutment of said piston members on said mandrels.